Since the organic thin film solar cell can be produced easily via a coating process under atmosphere or inert environment, it is expected to be a solar cell of next generation to drastically reduce power generation cost from the conventional silicon based solar cell. After provision of a bulk heterojunction type photoelectric conversion layer forming micro phase separation of a p-type organic semiconductor and an n-type organic semiconductor, remarkable technical progress has been recognized in improvement of the photoelectric conversion efficiency. A bulk heterojunction type organic solar cell (an organic photoelectric conversion element) has characteristics of charge separation with relatively high efficiency before deactivation of the exciton formed by light absorption, there is a problem to cause reduction of photoelectric conversion efficiency due to recombination of a part of free carriers having different charge since the generated free carrier occurs charge transfer in the bulk heterojunction layer by micro phase separation of an organic donor material or an organic acceptor material respectively.
As a countermeasure to the above problems, a technology improving photoelectric conversion efficiency by providing an exciton block layer proposed between the photoelectric conversion layer and the electrode to inhibit carrier recombination on an electrode is proposed (for example, Patent Document 1), and a technology improving photoelectric conversion efficiency by adding an aromatic compound containing an anion and a cation in a carrier transport layer provided between an electrode and power generation layer (for example, Patent Document 2).
However as a result of earnest study by the inventors it is recognized that, separation power of a reverse carrier is low by the carrier transport layer formed via the coating process described above, and recombination among free carriers having different charge on an electrode is not sufficiently inhibit. Further, it is recognized that efficiency reduces when it is stored at high temperature, and there is temperature dependence during power generation.